I have studied the plasticity in olfactory system induced by sensory experience. We have shown for the first time in the olfactory system, that a daily exposure to odorants during 10 days enhances rats' ability to discriminate between chemically similar odorants, an improvement of performances called perceptual learning (Mandairon et al., 2006c; Mandairon et al., 2006a). To go further, I have also studied the mechanisms involved in this learning including the plasticity of the bulbar network and the role of the neurogenesis which still occurs in the olfactory bulb of adult animals. We have shown that the improvement of olfactory performances, which is dependant of the NMDA receptors (Mandairon et al., 2006b), is correlated by an increase in local inhibitory interneuron responsiveness to odorants (Mandairon et al., 2007a) and an increase of neurogenesis (Mandairon et al, in preparation), contributing to experience-dependent changes in odorant discrimination.

To understand better the mechanisms involved in olfactory perception and knowing that the olfactory bulb receives massive centrifugal inputs we have characterised the role of neuromodulator systems, cholinergic and noradrenergic, on olfactory perceptual capacities. We have demonstrated that the cholinergic and noradrenergic systems are involved spontaneous olfactory discrimination.

I described a new form of olfactory plasticity induced by olfactory enrichment called perceptual learning. Also, I demonstrated some of the mechanisms underlying that learning. Olfactory perceptual learning is a relatively long-term increase in perceptual acuity and is critical for normal olfactory discrimination and so for animal's behaviour.